Light-weight, high-strength, and high-elasticity titanium alloy and implementation method thereof

ABSTRACT

A light-weight, high-strength, and high-elasticity titanium alloy and an implementation method thereof. The titanium alloy is specifically Ti-8Al-2V-1Cr-0.75Zr, wherein the content of Al is 7.0% to 9.5%, the content of V is 0.5% to 4.0%, the content of Cr is 0.5% to 3.5%, the content of Zr is 0.5% to 2.0%, and the balance is Ti. The titanium alloy is obtained by vacuum arc remelting(VAR), after mold pressing through the adoption of sponge titanium, vanadium, chromium, aluminum zirconium pure, pure aluminum, aluminum vanadium alloy mixed consumable electrode. The titanium alloy is simple in preparation processing steps, low in processing cost, easy in production, and is applicable to various application fields with a requirement for a low-density and high-strength titanium alloy.

This application claims priority to Chinese Patent Application Ser. No. CN201811007924.9 filed on 31 Aug. 2018.

TECHNICAL FIELD

The invention relates to the technical field of titanium alloy, in particular to an α+β two-phase titanium alloy SJ1100 with density less than 4.40 g/cm³, annealing state strength larger than 1100 MPa, elongation larger than 10%, and elastic modulus less than 130 GPa, and an implementation method thereof.

BACKGROUND ART

In recent year, since energy prices increase constantly, requirements for environments are stricter, and a light-weight requirement is proposed in automotive manufacturing industries as well. If a weight of a car can be reduced by 10%, oil consumption can be reduced by 8% to 10%.For every 1 kg weight reduction of an aircraft and an engine, a usage cost thereof can typically save $220-440/hour. Therefore, it is extremely urgent to increase a strength and weight ratio of materials.

Ti₃Al-base alloy belongs to a Ti—Al based intermetallic compound material, has outstanding characteristics of low density, high strength, good oxidation resistance and the like, and is considered to be an ideal structural material with light density and high temperature resistance for improving performance of an aero engine. However, since an intermetallic compound material has characteristics of an atom long range ordered arrangement and coexistence of a metal bond and a covalent bond, high temperature strength is excellent, and meanwhile, an alloy is relatively low in plasticity which is a maximum obstacle for engineering application. It is required to further adjust alloy components to improve plasticity and toughness of the alloy.

The high-strength titanium alloy refers to a titanium alloy with room temperature strength larger than 1100 MPa after annealing. In recent years, the high-strength titanium alloy has been rapidly developed to meet the demand for titanium for an aircraft structure. The high-strength titanium alloy mainly includes α+β titanium alloy, near-metastable β titanium alloy and metastable β titanium alloy. The high-strength titanium alloy is generally processed by a plastic method such as forging or rolling to obtain a fine grain structure, and further by heat treatment such as annealing, solid solution treatment, and aging to change morphology, a type, a size, a volume fraction and the like of the a or β phase in the structure so as to achieve a purpose of improving performance.

The titanium alloy is relatively large in a yield limit and elastic limit ratio, high in a yield ratio, large in an amount of deformation resistance and deformation rebound, relatively low in plasticity, difficult to deform, and complicated in preparation processing, therefore a manufacturing cost of the titanium alloy is high, which also has an influence on application and promotion of the titanium alloy to more fields.

SUMMARY OF THE INVENTION

To overcome the above-mentioned defects in the prior art, the invention provides a light-weight, high-strength, and high-elasticity titanium alloy and an implementation method thereof. The titanium alloy is simple in preparation processing steps, low in processing cost, easy in production, and is applicable to various application fields with a requirement for a low-density and high-strength titanium alloy.

The invention is implemented by the following technical scheme.

The invention relates to a light-weight, high-strength, and high-elasticity titanium alloy named SJ1100, which is Ti-8Al-2V-1Cr-0.75Zr, wherein the content of Al is 7.0% to 9.5%, the content of V is 0.5% to 4.0%, the content of Cr is 0.5% to 3.5%, the content of Zr is 0.5% to 2.0%, and the balance is Ti.

The content of Al is preferably 7.0% to 9.0%. Al is selected as a main alloy element to improve strength of the titanium alloy, stabilize the a phase in the titanium alloy, improve high temperature strength, and meanwhile reduce the density. If the content of Al is increased too much, forming ability of the titanium alloy will be reduced, therefore the content of Al is preferably 7.0% to 9.5%.

The content of V is preferably 0.5% to 3.5%. Since forming ability will be reduced due to an increase of the content of Al, density is ensured while the cold and Thermoforming ability is improved by adding a small amount of V. And the small amount of V with the same crystal structure as titanium is added to inhibit crystal nucleus and refine grains so as to ensure that the alloy has relatively high plasticity under a condition of high strength. Meanwhile, no precious metal Mo is added, resulting in a reduction in alloy cost.

The content of Cr is preferably 0.5% to 3.0%. A small amount of elements Cr and Zr can improve strength and oxidation resistance of the titanium alloy. The Cr is mainly used for solid solution strengthening to improve plasticity, toughness and hardenability of the alloy and to refine an as-cast microstructure of the alloy.

The content of Zr is preferably 0.5% to 1.8%. Zr is a neutral element and the titanium alloy can be strengthened by solid solution, which have certain effects of improving alloy strength, stabilizing the a phase and the β phase, and inhibiting generation of a ω phase. Meanwhile, Zr is added to inhibit oxidation inside the alloy, reduce elastic modulus of the alloy, and guarantee good processability of the alloy such as improving welding performance of the alloy.

The invention relates to a preparation method for the light-weight, high-strength, and high-elasticity titanium alloy SJ1100, including the steps of: through the adoption of sponge titanium, vanadium, chromium, aluminum zirconium pure, pure aluminum, aluminum vanadium alloy mixed consumable electrode, obtaining an alloy ingot by vacuum electric arc method of melting and forging on the alloy ingot under heating insulating at a temperature of 1000° C. to 1200° C.; performing blanking at 900° C. to 1100° C.; performing forging or hot rolling at 850° C. to 1000° C.; performing cold rolling after an annealing treatment of a forged finished product or a hot-rolled sheet to obtain a finished product; annealing at 600° C. to 900° C.; and finally performing pickling to prepare a titanium alloy finished product.

Purity of the titanium sponge which is produced by a metal thermal reduction method is 99.1% to 99.7%.

The vacuum electric arc remelting method which adopts, but is not limited to: Alloy shall be multiple melted. Melting cycle(s) prior to the final melting cycle shall be made using vacuum consumable electrode, The final melting cycle shall be made under vacuum using vacuum arc remelting (VAR) practice with no alloy additions permitted.

A temperature range of the cogging and forging for ingot is preferably 1000° C. to 1180° C.

A temperature range of the blanking forging is preferably 900° C. to 1080° C.

A temperature range of the forging or rolling is preferably 850° C. to 990° C.

The cold rolling adopts, but is not limited to, rolling, extrusion, stamping, upsetting and stretching, and the like.

A temperature of the annealing is preferably 620° C. to 880° C., and time is preferably 0.5 h to 2 h.

A process of the forging specifically includes: forging the alloy ingot to a tetragonal body; sequentially forging into a hexagonal and an octagonal cross section; and finally forging to prepare a blank. A temperature range of the alloy forging or rolling is preferably 850° C. to 990° C. and a deformation amount is 60% to 80%.

The rolling includes cold rolling after annealing, and a deformation amount thereof is 25% to 40%.

The alloy ingot is heated and heat-insulated at 1000° C. to 1200° C. for cogging and forging and is forged and blanked at 900° C. to 1100° C.

A specific temperature parameter of the forging is that a temperature of feeding the alloy ingot into a furnace is 600° C. to 900° C. and time for heat insulation is 1 h to 4 h; after heat insulation is finished, a temperature after temperature raising for 2 h to 4 h is 1100° C. to 1200° C., and time for heat insulation is 3 h to 7 h; and a temperature of returning to the furnace is 1000° C. to 1100° C. and a temperature of third returning to the furnace is 900° C. to 1000° C.

A temperature of pickling is 400° C. to 550° C., and time is 5 minutes to 30 minutes.

TECHNICAL EFFECT

Compared with the prior art, the invention selects Al as a main alloy element to improve strength of the titanium alloy, stabilize the a phase in the titanium alloy, improve high-temperature strength, and meanwhile reduce the density. Since the cold and Thermoforming ability will be reduced due to an increase of the content of Al, low density is ensured while the forming ability is improved by adding a small amount of V. And the small amount of V with the same crystal structure as titanium is added to inhibit crystal nucleus and refine grains so as to ensure that the alloy has relatively high plasticity under a condition of high strength. Meanwhile, no precious metal Mo is added, resulting in a reduction in alloy cost. A small amount of elements Cr and Zr is further added to improve strength and oxidation resistance. The Cr is mainly used for solid solution strengthening to improve plasticity, toughness and hardenability of the alloy and to refine an as-cast microstructure of the alloy. Zr is a neutral element and the titanium alloy can be strengthened by solid solution, which have certain effects of improving alloy strength, stabilizing the a phase and the β phase, and inhibiting generation of a ω phase. Meanwhile, Zr is added to inhibit oxidation inside the alloy, lower elastic modulus of the alloy, and guarantee good processablity of the alloy. Finally, density of the alloy is reduced to 4.39 g/cm³ and is measured to be 4.35 g/cm³.The tensile strength reaches 1100 MPa or more in an annealing state, the elastic modulus reaches 130 GPa or less, and meanwhile an elongation reaches 10% or more. The invention achieves a good combination of strength and plasticity which is not achieved by materials of the prior art, and has characteristics of light in weight, good in elastic modulus, and easy in production and processing.

DESCRIPTION OF EMBODIMENTS

The mass percentage content of the titanium alloy prepared according to an example is Al: 7.0% to 9.5%, V: 0.5% to 3.5%, Cr: 0.5% to 3.0%, Zr: 0.5% to 1.8%, and the balance being Ti. 15 KG V—Al—Cr, 3 KG pure zirconium, 28.3 KG pure aluminum, 0.67 KG V—Al 65:35, and the balance being Ti are mixed and suppressed to a 400 KG consumable electrode in the present example. An alloy ingot is melted and casted by an electric arc method in a vacuum consumable furnace, is cogged and forged under heating heat-insulating at a temperature of 1000° C. to 1180° C., and is formed to be a blank at 900° C. to 1080° C. The blank is heat-rolled at 850° C. to 990° C. The heat-rolled blank is annealed at 620° C. to 880° C., then cold-rolled, finally annealed at 620° C. to 880° C., and then pickled at 400° C. to 550° C. to prepare a titanium alloy blank finished product.

Finished products of 10.0 mm, 5.0 mm, 4.0 mm, and 2.8 mm are prepared as described above. Through properties testing, finished products of all process specifications meet a desired performance result.

EXAMPLE 1

Properties of 10.0 mm finished product in this example.

Yield Tensile Elastic Process Thickness strength strength Elongation modulus route (mm) (MPa) (MPa) (%) (KN/mm²) Process 1 10.54 T^(Note 1) 1026 1119 11.66 125.22 Process 2 10.49 T 1031 1130 11.92 129.52 Process 3 10.55 T 1053 1115 12.38 128.28 ^(Note 1)Tests taken transverse to the direction of rolling.

A specific operation of process 1 was as follows. Hot rolling and cogging were performed at 950° C. to 1050° C. and a deformation amount was 60% to 80%; a deformation amount at 900° C. to 1030° C. was 45% to 75%; and a finished product was prepared after pickling was performed at 400° C. to 550° C.

A specific operation of process 2 was as follows. Hot rolling and cogging were performed at 950° C. to 1050° C. and a deformation amount was 60% to 80%; a finished product specification was prepared by rolling with a deformation amount of 50% to 70% at 900° C. to 1030° C.;

annealing was performed at 780° C. to 860° C. and time for heat insulation was 0.5 h to 1.5 h; and finally a finished product was prepared after pickling was performed at 400° C. to 550° C.

A specific operation of process 3 was as follows. Hot rolling and cogging were performed at 950° C. to 1050° C. and a deformation amount was 60% to 80%; a finished product specification was prepared by rolling with a deformation amount of 50% to 75% at 900° C. to 1030° C.; annealing was performed at 750° C. to 850° C. and time for heat insulation was 0.5 h to 1.5 h; and finally a finished product was prepared after pickling was performed at 400° C. to 550° C.

EXAMPLE 2

Properties of 5.0 mm finished product in this example.

Yield Tensile Elastic Process Thickness strength strength Elongation modulus route (mm) (MPa) (MPa) (%) (KN/mm²) Process 4 5.08 L^(Note 2) 1042 1136 12.82 121.54 5.15 T^(Note 3) 1059 1152 13.30 122.30 Process 5 5.0 L 1026 1141 11.60 128.08 5.0 T 1019 1166 12.02 124.93 5.0 L 1022 1133 12.12 126.62 5.0 T 1030 1148 12.88 116.82 ^(Note 2)Tests taken longitudinal to the direction of rolling, the following is same. ^(Note 3)Tests taken transverse to the direction of rolling, the following is same.

A specific operation of process 4 was as follows. Hot rolling was performed at 920° C. to 1030° C. and a deformation amount was 40% to 70%; a finished product specification was prepared by rolling with a deformation amount of 50% to 70% at 900° C. to 1000° C.; and finally a finished product was prepared after pickling was performed at 400° C. to 550° C.

A specific operation of process 5 was as follows. Hot rolling was performed at 950° C. to 1050° C. and a deformation amount was 50% to 80%; a finished product specification was prepared by rolling with a deformation amount of 40% to 70% at 900° C. to 1030° C.; annealing was performed at 780° C. to 860° C. and time for heat insulation was 0.5 h to 1.5 h; and finally a finished product was prepared after pickling was performed at 400° C. to 550° C.

EXAMPLE 3

Properties of 4.0 mm finished product in this example.

Yield Tensile Elastic Process Thickness strength strength Elongation modulus route (mm) (MPa) (MPa) (%) (KN/mm²) Process 6 4.36 L 1031 1129 13.94 120.82 4.35 T 1045 1132 14.76 122.13 Process 7 4.34 L 1139 1151 13.12 118.08 4.36 T 1107 1137 13.86 118.93 4.38 L 1140 1141 12.84 116.62 4.22 T 1059 1138 13.42 116.97 Process 8 4.20 L 1129 1172 10.36 120.38 4.22 T 1119 1162 12.58 117.38

A specific operation of process 6 was as follows. Hot rolling was performed at 950° C. to 1050° C. and a deformation amount was 50% to 80%; rolling was performed at 900° C. to 1030° C. with a deformation amount of 40% to 70%; annealing was performed at 750° C. to 880° C. and time for heat insulation was 1 h to 2 h; a finished product specification was prepared by cold rolling; further annealing was performed at 780° C. to 860° C. and time for heat insulation was 1 h to 2 h; and finally a finished product was prepared after pickling was performed at 400° C. to 550° C.

A specific operation of process 7 was as follows. Hot rolling was performed at 950° C. to 1050° C. and a deformation amount was 50% to 80%; rolling was performed at 900° C. to 1000° C. with a deformation amount of 40% to 70%; annealing was performed at 700° C. to 850° C. and time for heat insulation was 0.5 h to 1.5 h; a finished product specification was prepared by cold rolling; further annealing was performed at 700° C. to 830° C. and time for heat insulation was 0.5 h to 1.5 h; and finally a finished product was prepared after pickling at 400° C. to 550° C.

A specific operation of process 8 was as follows. Hot rolling was performed at 950° C. to 1050° C. and a deformation amount was 50% to 80%; rolling was performed at 900° C. to 1000° C. with a deformation amount of 40% to 70%; annealing was performed at 700° C. to 850° C. and time for heat insulation was 0.5 h to 1.5 h; a finished product specification was prepared by cold rolling; further annealing was performed at 700° C. to 850° C. and time for heat insulation was 0.5 h to 1.5 h; pickling was performed at 400° C. to 550° C., then pressing and straightening were performed at 500° C. to 650° C., and time for heat insulation was 3 h to 6 h; and finally a finished product was prepared after pickling was performed at 400° C. to 550° C.

EXAMPLE 4

Properties of 2.8 mm finished product in this example.

Yield Tensile Elastic Process Thickness strength strength Elongation modulus route (mm) (MPa) (MPa) (%) (KN/mm²) Process 9 2.89 L 1087 1162 13.46 107.2 2.83 T 1041 1125 11.38 107.9 2.9 L 1090 1167 11.48 108.5 2.85 T 1037 1165 11.34 107.6

A specific operation of process 9 was as follows. Hot rolling and cogging were performed at 950° C. to 1050° C. and a deformation amount was 60% to 80%; rolling was performed at 900° C. to 1030° C. and a deformation amount was 45% to 75%; rolling was performed at 900° C. to 1000° C. and a deformation amount was 50% to 75%; annealing was performed at 750° C. to 850° C. and time for heat insulation was 0.5 h to 2 h; a finished product specification was prepared by cold rolling after pickling was performed at 400° C. to 550° C.; annealing was performed at 750° C. to 850° C. and time for heat insulation was 0.5 h to 2 h; and finally a finished product was prepared after pickling at 400° C. to 550° C.

Notes: In the table, L represents a longitudinal direction, i.e., a rolling direction of the blank, and T represents a transverse direction, i.e., perpendicular to the rolling direction.

Intermediate alloys 105 KG V—Al—Cr and 17 KG VAl65:35, 226 KG Al, 25 KG Zr, and the balance being Ti were adopted to prepare a 3000 KG electrode. The content of each alloy component for the example was preferably as follows. The content of V was 7.8% to 8.5%, the content of V was 1.7% to 2.5%, the content of Zr was 0.5% to 1.0%, the content of Cr was 1.0% to 2.0%, and the balance was Ti and other unavoidable impurities. The above-mentioned methods of melting, forging, rolling and annealing were repeated and optimized to prepare finished products with specifications of 12.0 mm, 5.6 mm, 5.1 mm and 4.1 mm. Through detection, finished products of all process specifications met a desired performance requirement.

EXAMPLE 5

Properties of 12.0 mm finished product in this example.

Yield Tensile Elastic Process Thickness strength strength Elongation modulus route (mm) (MPa) (MPa) (%) (KN/mm²) Process 10 12.0 L 1035 1125 15.10 126.56 12.0 T 1061 1137 15.88 129.50 Process 11 12.0 L 1110 1156 12.70 126.86 12.0 T 1127 1178 12.84 128.96

A specific operation of process 10 was as follows. Hot rolling and cogging were performed at 900° C. to 1050° C. and a deformation amount of the rolling was 60% to 80%; then rolling was performed at 880° C. to 1000° C. to prepare a finished product specification and a deformation amount was 50% to 70%; annealing was performed at 730° C. to 850° C. and time for heat insulation was 0.5 h to 2 h; and finally pickling was performed at 400° C. to 550° C. to prepare a finished product.

A specific operation of process 11 was as follows. Hot rolling and cogging were performed at 900° C. to 1050° C. and a deformation amount of the rolling was 60% to 80%; then rolling was performed at 880° C. to 1000° C. to prepare a finished product specification and a deformation amount was 50% to 70%; annealing was performed at 730° C. to 850° C. and time for heat insulation was 0.5 h to 2 h; then pickling was performed at 400° C. to 550° C.; pressing and straightening was performed at 500° C. to 620° C. and time for heat insulation was 2 h to 6 h; and finally pickling was performed at 400° C. to 550° C. to prepare a finished product.

EXAMPLE 6

Properties of 5.1 mm finished product in this example.

Yield Tensile Elastic Process Thickness strength strength Elongation modulus route (mm) (MPa) (MPa) (%) (KN/mm²) Process 12 5.1 L 1085 1159 13.04 126.60 5.1 T 1097 1162 13.46 128.25 Process 13 5.1 L 1062 1179 12.42 114.65 5.1 T 1103 1165 14.94 127.42

A specific operation of process 12 was as follows. Hot rolling and cogging were performed at 900° C. to 1050° C. and a deformation amount of the rolling was 60% to 80%; then rolling was performed at 880° C. to 1000° C. and a deformation amount was 50% to 70%; pickling was performed at 400° C. to 550° C.; then rolling was performed at 880° C. to 1000° C. and a deformation amount was 40% to 65%; pickling was performed at 400° C. to 550° C.; annealing was performed at 730° C. to 850° C. and time for heat insulation was 0.5 h to 2 h; pickling was performed at 400° C. to 550° C.; cold rolling was performed to prepare a finished product specification and a deformation amount of the rolling was 10% to 40%; annealing was performed at 750° C. to 850° C. and time for heat insulation was 0.5 h to 2 h; and finally pickling was performed at 400° C. to 550° C. to prepare a finished product.

A specific operation of process 13 was as follows. Hot rolling and cogging were performed at 900° C. to 1050° C. and a deformation amount of the rolling was 60% to 80%; then rolling was performed at 880° C. to 1000° C. and a deformation amount was 50% to 70%; pickling was performed at 400° C. to 550° C.; then rolling was performed at 880° C. to 1000° C. and a deformation amount was 45% to 65%; annealing was performed at 750° C. to 850° C. and time for heat insulation was 0.5 h to 1.5 h; and finally pickling was performed at 400° C. to 550° C. to prepare a finished product.

EXAMPLE 7

Properties of 4.1 mm finished product in this example.

Yield Tensile Elastic Process strength strength Elongation modulus route Thickness (MPa) (MPa) (%) (KN/mm²) Process 14 4.1 L 1080 1160 11.14 108.62 4.1 T 1117 1166 13.6 129.26 4.1 L 1095 1162 13.62 116.40 4.1 T 1084 1164 14.08 125.63

A specific operation of process 14 was as follows. Hot rolling and cogging were performed at 900° C. to 1050° C. and a deformation amount of the rolling was 60% to 80%; then rolling was performed at 880° C. to 1000° C. and a deformation amount was 50% to 70%; pickling was performed at 400° C. to 550° C.; then rolling was performed at 880° C. to 1000° C. and a deformation amount was 40% to 65%; pickling was performed at 400° C. to 550° C.; annealing was performed at 730° C. to 850° C. and time for heat insulation was 0.5 h to 2 h; pickling was performed at 400° C. to 550° C.; cold rolling was performed to prepare a finished product specification and a deformation amount was 20% to 40%; annealing was performed at 750° C. to 850° C. and time for heat insulation was 0.5 h to 2 h; and finally pickling was performed at 400° C. to 550° C. to prepare a finished product.

Alloy Density Measured Value

Sample No. 1 2 3 Average Measured 4.355 4.363 4.332 4.35 value (g/cm³) Theoretical 4.39 density (g/cm³)

Deformation process specification was as follows.

Heating Finishing Ingot Deformation temperature temperature deformation specification type (° C.) (° C.) (%)  500 KG Ingot forging 1100-1150 ≥750 64 Blank forging 1000-1100 ≥750 — Blank hot 1000  ≥700 68 rolling Hot rolling 960 ≥700 74 twice Cold rolling Room — 35 temperature 3000 KG Ingot forging 1100-1150 ≥750 74 Blank forging 1000-1100 ≥750 — Blank hot 960 ≥700 79 rolling Hot rolling 930 ≥700 70 twice Cold rolling Room — 35 temperature

In conclusion, a significant progress of the invention compared to the prior art is that the prepared titanium alloy SJ1100 has density less than 4.40 g/cm³, annealing state strength larger than 1100 MPa, elongation larger than 10%, and elastic modulus less than 130 GPa.

The foregoing detailed examples can be adjusted locally in different ways by those skilled in the art without departing from the principles and spirit of the invention. The scope of the invention is subjected to the claims and is not limited by the foregoing detailed examples. All implementations within the scope thereof are restricted by the invention. 

What is claimed is:
 1. A light-weight, high-strength, and high-elasticity titanium alloy SJ1100, specifically Ti-8Al-2V-1Cr-0.75Zr, wherein the content of Al is 7.0% to 9.5%, the content of V is 0.5% to 4.0%, the content of Cr is 0.5% to 3.5%, the content of Zr is 0.5% to 2.0%, and the balance is Ti.
 2. The titanium alloy SJ1100 according to claim 1, wherein a composition and content thereof were as follows: the content of Al is 7.0% to 9.0%, the content of V is 0.5% to 3.5%, the content of Cr is 0.5% to 3.0%, the content of Zr is 0.5% to 1.8%, and the balance is Ti.
 3. A method of preparing the light-weight, high-strength, and high-elasticity titanium alloy SJ1100 according to claim 1, the method comprising: through the adoption of sponge titanium, vanadium, chromium, aluminum zirconium pure, pure aluminum, aluminum vanadium alloy mixed consumable electrode, obtaining an alloy ingot by vacuum arc remelting (VAR) after mold pressing; performing cogging and forging on the alloy ingot under heating insulating at a temperature of 1000° C. to 1200° C.; performing blanking forging at 900° C. to 1100° C.; performing forging or rolling at 850° C. to 1000° C.; performing cold rolling after annealing treatment on a forged finished product or a hot-rolled sheet to obtain a finished product; annealing the finished product at 600° C. to 900° C.; and finally performing pickling to prepare a titanium alloy finished product.
 4. The method according to claim 3, wherein the purity of the sponge titanium which is a sponge metal titanium produced by a metal thermal reduction method is 99.1% to 99.7%.
 5. The method according to claim 3, wherein the temperature of the cogging and forging is 1000° C. to 1180° C., the temperature of the blanking forging is 900° C. to 1080° C., the temperature of the forging or rolling is 850° C. to 990° C., the temperature of the annealing is 620° C. to 880° C., and the time of the annealing is 0.5 h to 2 h.
 6. The method according to claim 3, wherein a process of the forging specifically includes: forging the alloy ingot to a tetragonal body; sequentially forging into a hexagonal and an octagonal cross section; and finally forging to prepare a blank, wherein an alloy forging or rolling temperature is 850° C. to 990° C. and a deformation amount is 60% to 80%.
 7. The method according to claim 3, wherein the rolling includes cold rolling after annealing and a deformation amount thereof is 25% to 40%.
 8. The method according to claim 3, wherein the alloy ingot is subjected to the cogging and forging under heating insulating at 1000° C. to 1200° C. and is subjected to the forging and blanking forging at 900° C. to 1100° C.
 9. The method according to claim 3, wherein specific temperature parameters of the forging are as follows: the temperature of feeding the alloy ingot into a furnace is 600° C. to 900° C. and the time for the heat insulating is 1 h to 4 h; after the heat insulating, the temperature is increased for 2 h to 4 h to 1100° C. to 1200° C., and the time for further heat insulating is 3 h to 7 h; and the temperature of returning to the furnace is 1000° C. to 1100° C. and the temperature of third returning to the furnace is 900° C. to 1000° C.
 10. The method according to claim 3, wherein the temperature of the pickling is 400° C. to 550° C., and the time is 5 minutes to 30 minutes. 